Java GenericsでDAO実装を簡素化させる - DAOパターン実装その２

// super dao interface
public interface IDao <T, PK extends Serializable> {
    public T get(PK pk);
    public List <T>getAll();
    public PK save(T entity);
    public void update(T entity);
    public void saveOrUpdate(T entity);
    public void delete(T entity);
}

//super abstract dao class
public abstract class AbstractDao <T, PK extends Serializable>implements IDao<T, PK> {
    private Class clz;
    
    public AbstractDao(Class clz) {
        this.clz = clz;
    }
    
    public T get(PK pk) {
        return (T)getSession().get(clz, pk);
    }
    public List <T>getAll() {
        return getSession().createCriteria(clz).list();
    }
    public PK save(T entity) {
        return (PK)getSession().save(entity);
    }
    public void update(T entity) {
        getSession().update(entity);
    }
    public void saveOrUpdate(T entity) {
        getSession().saveOrUpdate(entity);
    }
    public void delete(T entity) {
        getSession().delete(entity);
    }
    
    private Session session;
    protected Session getSession() {
        //wrap session in a class such as HibernateUtils, then you can use  HibernateUtils.getCurrentSession() for getting a session.
        //参考：ThreadLocal でHibernate Session を効率的に管理する
        return session;
    }
}

//persist entity
public class User {
    private String id;
    private String name;
    
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    
    //... setter/getter HERE
}

//User Dao interface
public interface IUserDao extends IDao <User, String> {
    //ここに注目！重複するような記述はありません！
    // all are empty
    // get/getAll/save/update/saveOrUpdate/delete以外の処理をここで記述する
}

//UserDao Implementation
public class UserDao extends AbstractDao <User, String> implements IUserDao {
    public UserDao() {
        super(User.class);
    }
    // or use the following constructor
    //public UserDao(Class<User> type) {
    //    super(type);
    //}
    
        //ここに注目！重複するような記述はありません！
    // get/getAll/save/update/saveOrUpdate/delete以外の処理をここで記述する
}

public class Test {

    public static void main(String[] args) {
        IUserDao userDao = new UserDao();
        User user = userDao.get("1");
        if (user != null) {
            System.out.println(user.getName());
        }
        
        List<User> userList = userDao.getAll();
        for (User u:userList) {
            System.out.println(user.getName());
        }
    }
}